feat: add warning metadata and summarisation result to response type

[lukeocodes]

Add typing for new response format supporting summarisation results and warning metadata.
e.g. output

{
  "metadata": {
    ...
    "warnings": [
      {
        "parameter": "summarize",
        "type": "unsupported_language",
        "message": "Summarization isn’t supported for <detected language>."
      }
    ]
  },
  "results": {
    ...
    "summary": {
      "result": "failure",
      "short": "The summarization feature is currently only available in English. Please check out our API documentation for more details."
    }
  }
}

and

{
  "metadata": {
    ...
    "warnings": [
      {
        "parameter": "filler_words",
        "type": "unsupported_model",
        "message": "Filler Words is not available for the specified model. For supported models, see our docs: <link>"
      },
      {
        "parameter": "numerals",
        "type": "deprecated",
        "message": "The numerals parameter is deprecated. Please use smart_format=true instead. For more information, see our docs: <link>"
      }
    ]
  },
  "results": {
    ...
  }
}